A RECONSIDERATION OF THE PROPERTIES OF A PULSED RUBY LASER IN RELATION TO MICROSURGERY

Abstract— The properties of a pulsed ruby laser beam focused through a triocular microscope were studied in relation to microsurgery. Quantitative studies on 'model tissues' with different absorbencies at 6943 Å revealed that the spot diameter of the focused microbeam was dependent upon several factors. It decreased with (1) a decrease in the absorption by the object at 6943 Å; (2) a decrease in the energy of the microbeam; and (3) an increase in the magnification of the microscope. The existence of the 'tube of effect' in the optical path of the focused micro-beam was realized by irradiating the object at different planes. The depth of the tube of effect increased with (1) increase in laser energy or (2) decrease in magnification. By employing certain plant species ( Spirogyra praetensis Transeau, Ulva lactuca Linnaeus, Porphyra miniata (Lyngbye) C. Agardh and Elodea sp.) the reaction of the protoplasm to the laser microbeam in terms of 'primary damage' and 'secondary damage' was defined. Based on these experimental data the concept of minimal visible spot size in laser microsurgery and its limitations are discussed.     

Synthesis of metal−organic complex arrays

The Merrifield solid-phase peptide synthesis technique has been adapted to the synthesis of homo- and heterometallic metal?organic complex arrays (MOCAs). A terpyridine-appended and Fmoc-protected L-tyrosine derivative was metalated with Pt(II), Rh(III), or Ru(II) ions in solution and sequentially coupled at the surface of functionalized polymeric resin to give a metal complex triad (Rh?Pt?Ru), tetrad (Ru?Rh?Pt?Pt), pentad (Rh?Pt?Ru?Pt?Rh), and hexad (Rh?Pt?Ru?Pt?Rh?Pt) with specific metal sequence arrangements. These were cleaved from the resin, and their character was confirmed by mass spectrometry.     

What do we know about three-periodic nets?

An account is given of various classifications of three-periodic nets. It is convenient to classify nets according to the nature of their maximum-symmetry embeddings. Other classifications, particularly in terms of the tilings that carry the nets, are also discussed. Although there is an infinity of possible nets, for certain types the number of possibilities is limited—there are for example exactly five regular nets. An account is given of the enumerations of various types of special structures such as sphere packings, the nets of simple tilings and self-dual tilings. Some databases of relevant structures and computer programs are described.     

Crystals as molecules: postsynthesis covalent functionalization of zeolitic imidazolate frameworks

A new crystalline zeolitic imidazolate framework, ZIF-90, was prepared from zinc(II) nitrate and imidazolate-2-carboxyaldehyde (ICA) and found to have the sodalite-type topology. Its 3D porous framework has an aperture of 3.5 A and a pore size of 11.2 A. The pores are decorated by the aldehyde functionality of ICA which has allowed its transformation to the alcohol functionality by reduction with NaBH4 and its conversion to imine functionality by reaction with ethanolamine to give ZIF-91 and ZIF-92, respectively. The N2 adsorption isotherm of ZIF-90 shows a highly porous material with calculated Langmuir and BET surface areas of 1320 and 1270 m2 g(-1). Both functionalized ZIFs retained high crystallinity and in addition ZIF-91 maintained permanent porosity (surface areas: 1070 and 1010 m2 g(-1)).     

Reticular chemistry of metal-organic polyhedra

Metal-organic polyhedra (MOPs), are discrete metal-organic molecular assemblies. They are useful as host molecules that can provide tailorable internal volume in terms of metrics, functionality, and active metal sites. As a result, these materials are potentially useful for a variety of applications, such as highly selective guest inclusion and gas storage, and as nanoscale reaction vessels. This review identifies the nine most important polyhedra, and describes the design principles for the five polyhedra most likely to result from the assembly of secondary building units, and provides examples of these shapes that are known as metal-organic crystals.     

Taxonomy of periodic nets and the design of materials

The concept of a natural tiling for a periodic net is introduced and used to derive a transitivity associated with the structure. It is accordingly shown that the transitivity provides a useful method of classifying polyhedra and nets. For design of materials to serve as targets for synthesis, structures with one kind of edge (edge transitive) are particularly important. Edge-transitive polyhedra, layers and 3-periodic nets are then described. Some other nets of special importance in crystal chemistry are also identified.     

Porous,Conductive Metal‐Triazolates and Their Structural Elucidation by the Charge‐Flipping Method

A new family of porous crystals was prepared by combining 1H‐1,2,3‐triazole and divalent metal ions (Mg, Mn, Fe, Co, Cu, and Zn) to give six isostructural metal‐triazolates (termed MET‐1 to 6). These materials are prepared as microcrystalline powders, which give intense X‐ray diffraction lines. Without previous knowledge of the expected structure, it was possible to apply the newly developed charge‐flipping method to solve the complex crystal structure of METs: all the metal ions are octahedrally coordinated to the nitrogen atoms of triazolate such that five metal centers are joined through bridging triazolate ions to form super‐tetrahedral units that lie at the vertexes of a diamond‐type structure. The variation in the size of metal ions across the series provides for precise control of pore apertures to a fraction of an Angstrom in the range 4.5 to 6.1 Å. MET frameworks have permanent porosity and display surface areas as high as some of the most porous zeolites, with one member of this family, MET‐3, exhibiting significant electrical conductivity.     

Transformation of a metal-organic framework from the NbO to PtS net

Two metal-organic frameworks (MOFs), MOF-501 and MOF-502, respectively, formulated as Co(2)(BPTC)(H(2)O)(5).G(x) and Co(2)(BPTC)(H(2)O)(DMF)(2).G(x) (BPTC = 3,3',5,5'-biphenyltetracarboxylate; G = guest molecules), have been synthesized and structurally characterized, and their topologies were found to be based on the NbO (MOF-501) and PtS (MOF-502) nets. Heating MOF-501 in solution results in the more thermodynamically favored MOF-502.